Deck 36: Quantum Physics

Question 1

Nitrogen molecules of mass,m = 4.648 * 10^-26 kg each,have a speed of 270 m/s and are incident on a double slit.How far apart are the double slits if a nitrogen molecule fringe pattern,with fringes 0.40 cm apart,is observed on a screen 60.0 cm in front of the slits.

A)5.28 * 10^-9 m
B)6.19 * 10^-9 m
C)7.18 * 10^-9 m
D)7.92 * 10^-9 m

Answer 1

7.92 * 10^-9 m

Question 2

A nitrogen molecule of mass,m = 4.648 * 10^-26 kg,has a speed of 270 m/s.Determine its deBroglie wavelength.

A)5.28 * 10^-11 m
B)6.19 * 10^-11 m
C)7.18 * 10^-11 m
D)7.92 * 10^-11 m

Answer 2

5.28 * 10^-11 m

Question 3

A 20.0-kg particle has a deBroglie wavelength of 10.0 cm.How fast is the particle moving?

A)1.30 * 10^-34 m/s
B)2.64 * 10^-34 m/s
C)3.31 * 10^-34 m/s
D)3.98 * 10^-34 m/s
E)4.40 * 10^-34 m/s

Answer 3

3.31 * 10^-34 m/s

Question 4

A 20.0 kg particle has a deBroglie wavelength of 10.0 cm.What is the smallest momentum uncertainty of the particle if its position uncertainty is 5.00 cm?

A)1.38 * 10^-33 kg·m/s
B)2.17 * 10^-33 kg·m/s
C)1.05 * 10^-33 kg·m/s
D)9.32 * 10^-32 kg·m/s
E)1.54 * 10^-33 kg·m/s

Question 5

The work function of a certain material is 4.9 eV.What is the photoelectric cut-off wavelength for this material?

A)1.3 * 10^-7 m
B)2.5 * 10^-7 m
C)3.3 * 10^-7 m
D)3.9 * 10^-7 m
E)4.4 * 10^-7 m

Question 6

During the photoelectric effect,that forms the basis of photovoltaic solar cells,a beam of monochromatic light consisting of an unknown number of photons knock electrons out of a metal producing an electrical current.For this effect,which statement is always true?

A)The kinetic energy of each electron depends on the intensity of the light beam.
B)The kinetic energy of each electron depends on the number of photons in the light beam.
C)The kinetic energy of each electron depends on the wavelength of the photons in the light beam.
D)All are correct.

Question 7

During Compton scattering,when a beam of monochromatic x-ray photons scatter off stationary electrons,their wavelength increases.What is the scattering angle relative to the direction of the incident photons which corresponds to the maximum possible increase in the wavelength of the photons?

A)0 ^$\circ$
B)90 ^$\circ$
C)180 ^$\circ$
D)There is no maximum value for the increase in wavelength.
E)The wavelength of the x-ray photons doesn't increase.It decreases.

Question 8

A 20.0 kg particle has a deBroglie wavelength of 10.0 cm.What is the smallest position uncertainty of the particle if its speed uncertainty is 3.31 * 10^-35 m/s?

A)7.15 cm
B)5.00 cm
C)8.33 cm
D)6.63 cm
E)7.97 cm

Question 9

A beam of monochromatic light has an intensity I and consists of an unknown number of photons.All of the photons have the same wavelength and frequency.The energy of just one of these photons is smallest when

A)the intensity of the light beam is largest.
B)the frequency of the photons is largest.
C)the wavelength of the photons is largest.
D)All are correct.

Question 10

At what frequency does the blackbody radiation from a microwave source have its maximum intensity? The temperature of the microwave source is 2.73 K.

A)3.41 * 10¹¹ Hz
B)2.39 * 10¹¹ Hz
C)1.95 * 10¹¹ Hz
D)2.83 * 10¹¹ Hz

Question 11

The photoelectric minimum (threshold)frequency for a material is 3.3 * 10^-7 m.What is the work function for this material?

A)9.2 eV
B)5.6 eV
C)3.8 eV
D)6.1 eV
E)4.9 eV

Question 12

The Pauli exclusion principle applies to

A)fermions only.
B)bosons only.
C)both fermions and bosons.
D)electrons only.

Question 13

The work function of a certain material is 4.9 eV.What is the photoelectric minimum (threshold)frequency for this material?

A)1.18 * 10¹⁵ Hz
B)2.23 * 10¹⁵ Hz
C)9.01 * 10¹⁴ Hz
D)3.48 * 10¹⁵ Hz
E)2.56 * 10¹⁵ Hz

Question 14

During Compton scattering,when a beam of monochromatic x-ray photons scatter off stationary electrons,their wavelength increases.What is the maximum possible increase?

A)2.43 pm
B)4.85 pm
C)There is no maximum value.
D)The wavelength of the x-ray photons doesn't increase.It decreases.

Question 15

At what wavelength does the blackbody radiation from a microwave source has its maximum intensity? The temperature of the microwave source is 2.73 K.

A)1.06 m
B)7.92 m
C)1.06 mm
D)7.92 mm

Question 16

The blackbody radiation from a microwave source has its maximum intensity at a wavelength of 0.792 mm.What is the temperature of the microwave source?

A)3.66 K
B)2.34 K
C)2.73 K
D)4.09 K

Question 17

A beam of monochromatic light has an intensity I and consists of an unknown number of photons.All of the photons have the same wavelength and frequency.The energy of just one of these photons is largest when

A)the intensity of the light beam is largest.
B)the frequency of the photons is largest.
C)the wavelength of the photons is largest.
D)All are correct.

Question 18

The photoelectric minimum (threshold)frequency for a material is 2.23 * 10¹⁵ Hz.What is the work function for this material?

A)8.3 eV
B)4.9 eV
C)11 eV
D)9.8 eV
E)9.2 eV

Question 19

A nitrogen molecule of mass,m = 4.648 * 10^-26 kg,has a deBroglie wavelength of 6.19 * 10^-11 m.Determine its its speed.

A)230 m/s
B)270 m/s
C)300 m/s
D)320 m/s

Question 20

A 20.0 kg particle has a deBroglie wavelength of 10.0 cm.What is the smallest speed uncertainty of the particle if its position uncertainty is 5.00 cm?

A)1.30 * 10^-35 m/s
B)2.64 * 10^-35 m/s
C)3.31 * 10^-35 m/s
D)3.98 * 10^-35 m/s
E)5.27 * 10^-35 m/s

Question 21

X-rays having energy of 350.0 keV undergo Compton scattering from a target.The scattered rays have a kinetic energy of 300 keV.At what angle,relative to the incident rays ar they scattered?

A)40.9 ^$\circ$
B)32.1 ^$\circ$
C)36.4 ^$\circ$
D)30.0 ^$\circ$
E)43.9 ^$\circ$

Question 22

Alpha particles (m = 6.6 * 10-27 kg,q = +2e)are accelerated through a potential difference of 11,100V,what is their de Broglie wavelength?

A)1.9 * 10^-49 m
B)1.5 * 10^-15 m
C)9.7 * 10^-14 m
D)4.5 * 10^-12 m
E)9.0 * 10^-12 m

Question 23

A particle accelerator boosts a proton's kinetic energy so that the de Broglie wavelength of the proton is 4.2 * 10^-15 m.What is the kinetic energy of the proton?

A)3.0 * 10⁸ eV
B)4.5 * 10⁷ eV
C)5.2 * 10⁶ eV
D)6.2 * 10³ eV
E)1.0 eV

Question 24

What is the ratio of deBroglie wavelengths of a 100 MeV kinetic energy proton to a 100 MeV kinetic energy electron?

A)0.02
B)0.23
C)2.3
D)23.0
E)230

Question 25

An electron is travelling at 0.7c.What is the deBroglie wavelength of this electron?

A)2.47 pm
B)3.48 pm
C)2.74 nm
D)1.85 µm
E)3.26 mm

Question 26

X-rays with a wavelength of 7.02 * 10^-12 m strike a stationary electron and the reflected photon is scattered 75 degrees relative to the incident photon.What is the wavelength of the scattered photon?

A)1.80 * 10^-12 m
B)4.59 * 10^-12 m
C)8.82 * 10^-12 m
D)It could have any wavelength of 7.02 * 10^-12 or longer.
E)It could have any wavelength of 7.02 * 10^-12 or shorter.

Question 27

What is the maximum speed of a 0.25-kg ball for it to be diffracted when passing through a 0.85-m wide doorway? (Hint: use the condition for diffraction of w $\le$ 10 $\lambda$ .)

A)3.1 * 10^-32 m/s
B)2.7 * 10^-32 m/s
C)4.6 * 10^-32 m/s
D)1.8 * 10^-32 m/s
E)0.53 * 10^-32 m/s

Question 28

X-rays having energy of 450.0 keV undergo Compton scattering from a target.The scattered rays are detected at 20.0 ^$\circ$ relative to the incident rays.The energy of the recoiling electron is

A)284 keV.
B)25.2 keV.
C)297 keV.
D)22.6 keV.
E)255 keV.

Question 29

Photons with energy of 2.95 eV illuminate a metal surface and it is found that voltage of 0.65 V is required to stop all the electrons that are ejected from the metal by this light.What is the metal?

A)potassium
B)uranium
C)magnesium
D)calcium
E)cesium

Question 30

A 71-kg sprinter runs at a speed of 12.1 m/s.What is the minimum uncertainty in his position?

A)1.0 * 10^-38 m
B)6.1 * 10^-38 m
C)4.7 * 10^-37 m
D)4.4 * 10^-36 m
E)There is no limit.

Question 31

A nocturnal bird's eye can to detect 20 photons per second of monochromatic light with a wavelength of 523 nm.The corresponding power of monochromatic light a nocturnal bird's eye can detect is

A)5.31 * 10^-16 W.
B)3.16 * 10^-17 W.
C)8.92 * 10^-17 W.
D)2.33 * 10^-18 W.
E)7.61 * 10^-18 W

Question 32

Find the largest possible wavelength for electrons (m = 9.11 *10^-31kg emitted from sodium (work function is 3.68 * 10^-19 J)when ultra-violet light (E = 5.90 * 10^-19 J)shines on it.

A)6.39 * 10^-10 m
B)8.10 * 10^-10 m
C)1.04 * 10^-9 m
D)1.47 * 10^-9 m
E)There is no maximum wavelength.

Question 33

A nocturnal bird's eye can to detect monochromatic light of frequency 6.38 * 10¹⁴ Hz with a power as small as 2.1 * 10^-17 W.What is the corresponding number of photons per second a nocturnal bird's eye can detect?

A)30
B)40
C)50
D)60
E)70

Question 34

An einstein (E)is a unit of measurement equal to Avogadro's Number (6.02 * 10²³)of photons.How much energy is contained in one einstein of red light ( $\lambda$ = 650 nm)?

A)0.18 MJ
B)0.93 MJ
C)1.1 MJ
D)3.9 MJ
E)6.1 MJ

Question 35

X-rays having energy of 350.0 keV undergo Compton scattering from a target.The scattered rays are detected at 30.0 ^$\circ$ relative to the incident rays.The energy of the scattered x-ray is

A)467 keV.
B)216 keV.
C)385 keV.
D)154 keV.
E)321 keV.

Question 36

Which of the following has the smallest deBroglie wavelength?

A)an electron travelling at 80% the speed of light
B)a proton travelling at 20% the speed of light
C)a carbon nucleus travelling at 70% the speed of light
D)a helium nucleus travelling at 80% the speed of light
E)a lithium nucleus travelling at 50% the speed of light

Question 37

X-rays undergo Compton scattering from a target.The scattered rays have an energy of 300 keV and are detected at 30.0 ^$\circ$ relative to the incident rays.The energy of the incident x-ray is

A)289 keV.
B)412 keV.
C)350 keV.
D)341 keV.
E)326 keV.

Question 38

Nitrogen molecules of mass,m = 4.648 * 10^-26 kg each,and are incident on a double slit.The spacing between the two slits is 5.28 * 10^-9 m.A nitrogen molecule fringe pattern,with fringes 0.40 cm apart,is observed on a screen 60.0 cm beyond the double slit.What is the speed of the nitrogen molecules?

A)358 m/s
B)405 m/s
C)270 m/s
D)179 m/s

Question 39

Nitrogen molecules of mass,m = 4.648 * 10^-26 kg each,have a speed of 270 m/s and are incident on a double slit.The spacing between the two slits is 5.28 * 10^-9 m.A nitrogen molecule fringe pattern is observed on a screen 60.0 cm beyond the double slit.How far apart are adjacent fringes on the screen?

A)0.40 cm
B)0.60 cm
C)0.70 cm
D)0.50 cm

Question 40

A soldering iron glows at 372 $\lambda$ C.What is the dominant wavelength emitted by the iron?

A)270 µm
B)11 µm
C)7.8 µm
D)4.5 µm
E)650 nm

Question 41

Through what potential difference must an electron be accelerated to have a wavelength of 632.8 nm corresponding to the wavelength of the red light of a He-Ne laser?

A)3.77 * 10^-6 V
B)5.56 * 10^-4 V
C)1.25 * 10^-2 V
D)3.77 V

Question 42

A metal has a chemical potential of 8 eV.The probability that an electron will occupy a state with E = 8.1 eV is 0.13.What is the temperature?

A)824 K
B)435 K
C)351 K
D)600 K

Question 43

How many photons of green light with a wavelength of 500 nm are necessary to have a total energy of 1.0 $\mu$ J?

A)2
B)2.5 * 10¹²
C)6.0 * 10¹⁴
D)1.6 * 10³¹
E)3.0 * 10³³

Question 44

The intensity of the radiation from the sun has a maximum around 550 nm.The surface temperature of the Sun is

A)15939 K.
B)9543 K.
C)7856 K.
D)5269 K.

Question 45

A pair of silver plates in a vacuum are separated by 1 cm and have a potential difference of 2.0 kV between them.What is the largest wavelength of light that can be shined on the cathode to produce a current through the anode?

A)1.2 * 10^-11 m
B)8.0 * 10^-11 m
C)9.8 * 10^-11 m
D)6.2 * 10^-10 m
E)1.2 * 10^-9 m

Question 46

Assume all the power consumed by a 75 W light bulb is emitted by the filament,which you can treat as a black-body.Treat the filament as a cylinder of diameter 1.0 mm and length 1.5 cm.What is the temperature of the filament?

A)1300 K
B)2300 K
C)2500 K
D)3100 K
E)18,000 K

Question 47

The probability that an electron will occupy a state with E = 8.10 eV at 600 K is 0.125.What is the chemical potential of the metal?

A)8.00 eV
B)8.08 eV
C)7.96 eV
D)8.04 eV

Question 48

A proton (rest mass 938.3 MeV/c²)is confined to a small region of space 2.0 nm wide.What is the uncertainty on its speed due to this confinement?

A)32 m/s
B)63 m/s
C)400 m/s
D)200 m/s

Question 49

What is the de Broglie wavelength of a baseball (mass 145 g)travelling at major league fastball speeds (99 mph)?

A)1.0 * 10^-34 m
B)3.1 * 10^-26 m
C)1.5 * 10^-32 m
D)5.1 * 10^-41 m
E)4.6 * 10^-24 m

Question 50

Given the work function of sodium is 2.75 eV,what is the stopping potential in an experiment using sodium cathodes at 360 nm?

A)1.1 V
B)0.7 V
C)4.55 V
D)0.22 V

Question 51

A metal has a chemical potential of 8 eV.What is the probability that an electron will occupy a state with E = 8.1 eV at 600 K?

A)0.02
B)0.09
C)0.13
D)0.25

Question 52

Which one of the following statements is true if the intensity of a light beam is increased while its frequency is kept the same?

A)The photons gain higher speeds.
B)The energy of the photons is increased.
C)The number of photons per unit time is increased.
D)The wavelength of the light is increased.

Question 53

The work functions for three metals X,Y.and Z are 4,5,and 6 eV,respectively.Photoelectrons are created when UV light shines on these metals.The photoelectrons from which metal would have the largest stopping voltage?

A)Z
B)Y
C)X

Question 54

An electron is confined to a box with a dimension of 20 $\mu$ m.If we have done our best to have the electron be at rest,within what range is its velocity likely to be found?

A) $\pm$ 0.2 m/s
B) $\pm$ 1.2 m/s
C) $\pm$ 5.8 m/s
D) $\pm$ 0.9 m/s

Question 55

X-rays of wavelength 8.9 pm are Compton scattered.What is the longest wavelength X-rays emitted in the process?

A)8.9 pm
B)12.5 pm
C)13.8 pm
D)16.7 pm
E)18.4 pm

Question 56

Assume all the power consumed by a 75 W light bulb is emitted by the filament,which you can treat as a black-body.Treat the filament as a cylinder of diameter 1.0 mm and length 2.0 cm.What is the peak wavelength of the lightbulb's emission spectrum?

A)1.3 $\mu$ m
B)2.2 $\mu$ m
C)1.4 $\mu$ m
D)0.93 $\mu$ m
E)1.2 $\mu$ m

Question 57

What is the wavelength of an electron which is accelerated from rest through a potential difference of 10^-5 V?

A)287 nm
B)389 nm
C)122 nm
D)400 nm

Question 58

Pauli exclusion principle states that which two particles can not occupy the same quantum state at the same time and at the same location?

A)fermions
B)neutrons
C)protons
D)electrons
E)All are correct.

Question 59

What is the minimum wavelength of light which can cause electron emission from copper?

A)263 nm
B)424 nm
C)678 nm
D)1435 nm
E)2345 nm

Question 60

A particular metal is illuminated by UV photons of wavelength 210 nm,and electrons up to 1.25 eV are emitted from the surface.What is the maximum KE of photoelectrons emitted when the UV photons are,instead,175 nm in wavelength?

A)1.18 eV
B)2.44 eV
C)5.90 eV
D)7.09 eV

Question 61

A 2 MeV x-ray photon is scattered from a free electron at rest into an angle of 45 ^$\circ$ .What is the wavelength of the scattered photon?

A)0.62 pm
B)0.71 pm
C)1.10 pm
D)1.33 pm
E)1.72 pm

Question 62

If a black body emits radiation at a temperature T,what would happen if it were heated to 2T?

A)The threshold wavelength would double.
B)The total energy emitted would double.
C)The spectrum shape would not change,but energy emitted would go up a factor of 16.
D)The peak wavelength would double.
E)The peak wavelength would be halved.

Question 63

A helium-neon laser puts out a beam of red light with frequency 4.74 * 10¹⁴ Hz.Determine the energy of each photon at that frequency.

A)1.96 eV
B)2.50 eV
C)8.81 eV
D)13.6 eV
E)25.0 eV

Question 64

If a particle has a rest mass of 9.1 * 10^-29 kg,what speed (m/s)would give it a de Broglie wavelength of 3.63 * 10^-9 m?

A)2 * 10 ^-7
B)2 * 10 ³
C)5 * 10 ^-3
D)5 * 10 ^-2
E)5

Question 65

Protons and neutrons are fermions.The nucleus of helium-4 contains two protons and two neutrons.Which of the following spin states are allowed for the nucleus of a helium-4 atom?

A)both protons spin up,both neutrons spin up
B)both protons spin up,both neutrons spin down
C)one proton and one neutron spin up and one proton and one neutron spin down
D)All are correct.
E)None are correct.

Question 66

The uncertainty principle says that for a given particle,one cannot determine precisely at the same time

A)position and momentum.
B)energy and position.
C)velocity and momentum.
D)velocity and energy.
E)energy and momentum.

Question 67

If a metal has a work function 4.3 eV what is the minimum frequency for photo-emission?

A)3.5 * 10⁸ Hz
B)3.0 * 10¹⁰ Hz
C)10.0 * 10⁸ Hz
D)1.04 *10¹⁵ Hz
E)1.0 Hz

Question 68

If light of wavelength 320 nm causes a 2.1 eV photon to be emitted from a metal surface,which of the following statements holds?

A)The work function must be greater than 2.1 eV.
B)The work function must be less than 1.8 eV.
C)The work function must be 3.9 eV.
D)The cut-off wavelength for photo emission is less than 320 nm.
E)The energy of a 320 nm photon must be 2.1 eV.